Fabio, Larry, Uri,
I notice VXLAN-GPE is on the IETF standards track.
It will need to specify support for propagation of the ECN field between
inner and outer for cases when there is (or might be) an IP header (v4
or v6) within the L2 encapsulation, and when the outer is IP (v4 or v6).
I believe ECN propagation between inner and outer is already in the
Linux code for VXLAN, but it's not specified in RFC7348, so other
implementations might overlook it. Given that ECN is heavily used in DCs
(e.g. for DCTCP), this is a significant omission.
Please refer to draft-ietf-tsvwg-rfc6040update-shim
<https://tools.ietf.org/html/draft-ietf-tsvwg-rfc6040update-shim> and
RFC6040.
I will warn you that, unless you believe that all existing VXLAN
implementations already support ECN, this will not be just a
straightforward case of referencing the appropriate RFCs. If there might
be non-ECN VXLAN decapsulators out there, the tunnel ingress will have
to know (by config or capability negotiation) whether the egress
supports ECN propagation, and if not, switch to 'compatibility mode'
(zeroing the outer ECN field). That could require definition of a
capability parameter during tunnel set-up (unless you envisage tunnel
set up will always be by administrative config).
Cheers
Bob
--
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Bob Briscoehttp://bobbriscoe.net/
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